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ATP splitting by half the cross-bridges can explain the twitch energetics of mouse papillary muscle
Australien.
Australien.
2006 (English)In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 573, no Pt 1, p. 5-15Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to quantify the fraction of cross-bridges that cycle during a cardiac twitch. Measurements of the energetics of contracting left ventricular mouse papillary muscle were made in vitro (27 degrees C) using the myothermic technique. Enthalpy output was partitioned into force-dependent and force-independent components using 2,3-butanedione monoxime (BDM) to selectively inhibit cross-bridge cycling. For isometric contractions and a contraction frequency of 2 Hz the net enthalpy output was 5.7 +/- 0.8 mJ g(-1) twitch(-1) and initial enthalpy output was 2.3 +/- 0.3 mJ g(-1) twitch(-1) (n = 11). Assuming that low concentrations of BDM did not affect Ca2+ cycling, force-independent enthalpy output was 18.6 +/- 1.9% (n = 7) of the initial enthalpy output. Enthalpy output decreased with increased contraction frequency but was independent of shortening velocity. On the basis of these values, it was calculated that the twitch energetics were consistent with ATP splitting by half the cross-bridges and the pumping of one Ca2+ into the sarcoplasmic reticulum for every three cross-bridge cycles. The simplest interpretation is that half the cross-bridges completed one ATP-splitting cycle in each twitch. The lack of influence of shortening velocity on energy cost supports the idea that the amount of energy to be used is determined early in a twitch and is not greatly influenced by events that occur during the contraction.

Place, publisher, year, edition, pages
2006. Vol. 573, no Pt 1, p. 5-15
National Category
Physiology
Identifiers
URN: urn:nbn:se:hkr:diva-17370DOI: 10.1113/jphysiol.2006.104992ISI: 000237397000004PubMedID: 16497711OAI: oai:DiVA.org:hkr-17370DiVA: diva2:1147726
Available from: 2017-10-08 Created: 2017-10-08 Last updated: 2018-01-13Bibliographically approved

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CiteExportLink to record
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Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
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  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
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  • asciidoc
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